Does the existence of nuclear weapons create a safer world?
Obviously, we'd be better off if nukes did not exist. But they do, and as such America having the most makes it much safer than if we get rid of them and let Iran, NK, China, and Pakistan control them. Disarming is pipe dream. We would be destroyed.
You can either have a bunch of guys holding guns to each others' heads in a Mexican standoff (MAD), or you can have a bunch of dudes beating the crap out of each other non-stop (pre-MAD). Pick your poison.
MAD is just one crazy crazy policy.
When both sides have nuclear weapons it's the only viable policy, because the world will never go back to the pre-nuclear days.
Though I get what you're saying, I'm not putting nuclear disarmament out of the realm of possibility...
All it takes is one lunatic with the wrong button in front of him, and BOOM!